import mysql.connector
from mysql.connector import errorcode
from .config import settings
from app.core.logger import get_logger

logger = get_logger(__name__)

# 全局的连接池
db_connection_pool = None

import mysql.connector
from mysql.connector import errorcode
from .config import settings
from app.core.logger import get_logger

logger = get_logger(__name__)

# 全局的连接池
db_connection_pool = None


def init_database():
    """
    初始化数据库：如果数据库或表不存在，则创建它们。
    """
    logger.info("--- 开始初始化数据库 ---")

    try:
        cnx = mysql.connector.connect(**settings.DATABASE_CONFIG)
        cursor = cnx.cursor()

        cursor.execute(f"CREATE DATABASE IF NOT EXISTS {settings.DB_NAME} DEFAULT CHARACTER SET 'utf8mb4'")
        logger.info(f"数据库 '{settings.DB_NAME}' 已准备就绪。")
        cnx.database = settings.DB_NAME

        # 1. 创建 card_images 表 (因为它被 cards 表引用)
        card_images_table = (
            f"CREATE TABLE IF NOT EXISTS `{settings.DB_IMAGE_TABLE_NAME}` ("
            "  `image_id` INT AUTO_INCREMENT PRIMARY KEY,"
            "  `image_name` VARCHAR(255) NULL,"
            "  `image_path` VARCHAR(512) NOT NULL,"
            "  `detection_json` JSON NOT NULL COMMENT '原始检测JSON数据',"
            "  `modified_json` JSON NULL COMMENT '修改后的JSON数据',"
            "  `created_at` TIMESTAMP DEFAULT CURRENT_TIMESTAMP,"
            "  `updated_at` TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT 'JSON数据最后修改时间'"
            ") ENGINE=InnoDB COMMENT='存储所有卡牌的图片及检测数据'"
        )
        cursor.execute(card_images_table)
        logger.info(f"数据表 '{settings.DB_IMAGE_TABLE_NAME}' 已准备就绪。")

        # 2. 创建 cards 表 (不带外键)
        cards_table = (
            f"CREATE TABLE IF NOT EXISTS `{settings.DB_CARD_TABLE_NAME}` ("
            "  `card_id` INT AUTO_INCREMENT PRIMARY KEY,"
            "  `card_name` VARCHAR(255) NULL COMMENT '卡牌的通用名称',"
            "  `front_face_id` INT NULL,"
            "  `back_face_id` INT NULL,"
            "  `front_edge_id` INT NULL,"
            "  `back_edge_id` INT NULL,"
            "  `created_at` TIMESTAMP DEFAULT CURRENT_TIMESTAMP,"
            "  `updated_at` TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP"
            ") ENGINE=InnoDB COMMENT='存储实体卡牌及其核心图片引用'"
        )
        cursor.execute(cards_table)
        logger.info(f"数据表 '{settings.DB_CARD_TABLE_NAME}' 已准备就绪。")

        # 3. 为 cards 表添加外键约束 (如果它们不存在)
        # 这是一个更健壮的方法，可以重复运行而不会出错
        foreign_keys = {
            "fk_front_face": "front_face_id",
            "fk_back_face": "back_face_id",
            "fk_front_edge": "front_edge_id",
            "fk_back_edge": "back_edge_id"
        }
        for fk_name, col_name in foreign_keys.items():
            try:
                # 检查外键是否存在
                cursor.execute(f"""
                    SELECT COUNT(*) FROM information_schema.KEY_COLUMN_USAGE
                    WHERE TABLE_SCHEMA = '{settings.DB_NAME}'
                    AND TABLE_NAME = '{settings.DB_CARD_TABLE_NAME}'
                    AND CONSTRAINT_NAME = '{fk_name}';
                """)
                if cursor.fetchone()[0] == 0:
                    alter_query = (
                        f"ALTER TABLE `{settings.DB_CARD_TABLE_NAME}` "
                        f"ADD CONSTRAINT `{fk_name}` "
                        f"FOREIGN KEY (`{col_name}`) "
                        f"REFERENCES `{settings.DB_IMAGE_TABLE_NAME}`(`image_id`) "
                        "ON DELETE SET NULL"
                    )
                    cursor.execute(alter_query)
                    logger.info(f"为表 '{settings.DB_CARD_TABLE_NAME}' 添加了外键 '{fk_name}'。")
            except mysql.connector.Error as err:
                # 1060: Duplicate column name; 1061: Duplicate key name; 1826: Duplicate foreign key
                if err.errno in [1060, 1061, 1826]:
                    logger.warning(f"外键 '{fk_name}' 可能已存在。跳过。")
                else:
                    raise err

    except mysql.connector.Error as err:
        logger.error(f"数据库初始化失败: {err}")
        exit(1)
    finally:
        if 'cursor' in locals() and cursor:
            cursor.close()
        if 'cnx' in locals() and cnx.is_connected():
            cnx.close()

    logger.info("--- 数据库初始化完成 ---")


def load_database_pool():
    """
    在应用启动时创建数据库连接池。
    """
    global db_connection_pool
    if db_connection_pool is None:
        logger.info("--- 创建数据库连接池 ---")
        try:
            db_connection_pool = mysql.connector.pooling.MySQLConnectionPool(
                pool_name="mypool",
                pool_size=5,  # 池中保持的连接数
                **settings.DATABASE_CONFIG_WITH_DB
            )
            logger.info("--- 数据库连接池创建成功 ---")
        except mysql.connector.Error as err:
            logger.error(f"创建数据库连接池失败: {err}")
            exit(1)


def close_database_pool():
    """
    在应用关闭时，不需要手动关闭连接池，连接器会自动处理。
    这个函数留作备用。
    """
    logger.info("--- 数据库连接池将自动关闭 ---")


# --- FastAPI 依赖注入 ---
def get_db_connection():
    """
    一个FastAPI依赖项，用于从池中获取数据库连接。
    它确保连接在使用后返回到池中。
    """
    if db_connection_pool is None:
        raise RuntimeError("数据库连接池未初始化")

    db_conn = None
    try:
        db_conn = db_connection_pool.get_connection()
        yield db_conn
    except mysql.connector.Error as err:
        logger.error(f"获取数据库连接失败: {err}")
        # 这里可以根据需要抛出HTTPException
    finally:
        if db_conn and db_conn.is_connected():
            db_conn.close()